***Do this modification at your own risk, I have not tried this yet and cannot confirm that it will work***

After talking to Tubular Joe for a few minutes, he explained how to rewire the input tubes to use 12AX7's rather than 6AX7's.

He explained that pins 4 and 5 on the 12AX7's are two 6.3v paths and pin 9 is the other end of said path. If you want to wire the tubes in this perticular way, you must run the tubes in parallel instead of the configuration that Bob has us running the heater wires for the 6AX7's.

Here is a photo of two different paths for the two different tubes:

RIP BillD

BillD wrote:Well, some people are glass half empty people and some are glass half full. Being an engineer, I just think the glass is the wrong size.

We spoke to Joe again and we asked him about the pros and cons of going to the 12AX7 and he said you would get less noise out of ANY 12AX7 than the 6AX7. Joe said that the Russian 6AX7 were cheaper to get than the 12AX7s and that was the reason Bob went with them... He also said that 12AX7's are a much more flexible in the brand names and qualities.

I picked up some shuguang 6AX7 tubes and they are stellar. However, for simplicity, 12ax7 is the way to go. The Commie output tubes are still working fine. I have been running the amp every day on Snell model B speakers without a hitch.